The influence of fibre wall thickness and fibril angle on fibre development in the TMP process

This study was designed to clarify the effect of fibril angle and fibre wall thickness on energy consumption and fibre development in the TMP process. Six logs of Scots pine and six logs of Norway spruce were selected so that the fibril angle and fibre wall thickness varied independently. The wood logs were chipped in a laboratory chipper and refined in four stages in a laboratory refiner. The investigation showed that differences in fibril angle can not explain the differences in behaviour between pine and spruce during TMP refining. Raw materials with thicker fibre walls produce more fines and external fibrillation and thus a lower SEC at a given freeness, however the effect does not seem to be strong enough to explain the difference between pine and spruce.